OFDM (Orthogonal Frequency Division Multiplexing, orthogonal frequency division multiplexing) is a basic transmission manner for current wireless communication, and is widely used in wireless communications systems such as LTE, WiMAX, and WiFi. In addition, the OFDM is further used in fixed network transmission, such as transmission by means of optical fibers, copper strands, or cables. The basic principle of the OFDM is to reduce, within a range allowed by subcarrier orthogonality, a subcarrier interval to the minimum, so as to ensure that multiple parallel paths that do not interfere with each other are formed while frequency utilization efficiency of a system can be improved. If subcarriers, which do not interfere with each other, of the OFDM are allocated to multiple users, the OFDM can be used to implement access or data transmission of the multiple users, and this is OFDMA (Orthogonal Frequency Division Multiple Access, orthogonal frequency division multiple access). However, in the prior art, data transmission efficiency is relatively low in an OFDMA scenario.